stored grain insect pests - the lsu agcenter
TRANSCRIPT
Stored Grain Insect Pests
• Primary Pests or Internal Feeders
– Attack whole grains
– Larvae feed and develop within the kernel
• Secondary Pests or External Feeders• Secondary Pests or External Feeders
– Feed on grain dust and broken kernels
– Can not damage whole grain
– Follow internal feeders, i.e. damaged grain
– Grain in poor condition, microbial activity.
Primary Pests
• Beetles
– Granary Weevil
– Rice Weevil
– Maize Weevil
• Moths
– Angoumois Grain
Moth
– Maize Weevil
– Lesser Grain
Borer
Primary FeedersBeetles
• Very small, 1/8 inch
• Dark or reddish-• Dark or reddish-
brown color
• Weevils have snout
• Weevil larva is a
legless grub
Rice Weevil
• Small pits/punctures on surface of thorax
• Two light colored spots on each wing cover
• Life cycle requires 28 or Spots • Life cycle requires 28 or more days.
• Female can lay up to 300 or 400 eggs.
• Females can live up to 4 or 5 months.
1/8 inch
Photo credit: Oklahoma State University
Spots
Rice Weevil
• Adult can fly.
• Infest grain in the field
• Adult weevil and grub (larvae) feed on whole grain.
Photo credit: University of Florida
whole grain.
• Adult drills whole in grain and then deposits egg.
• Requires grain moisture > 12%.
Lesser Grain Borer
• Slender, cylindrical form; head pointed downward
• Adult beetle and larvae attack
whole grain.
• Adults lay eggs outside of grain
kernel and larvae bore in.
1/8 inch
• Life cycle is approximately one month.
• Female lays up to 300 to 500
eggs.
• Can tolerate dryer grain, i.e. 8-
9%
• Infested grain has a slightly sweet, pungent odor.
Photo credit: Texas A&M University
Photo credit: Clemson University
Angoumois Grain Moth
• Caterpillar (larvae) is the damaging stage
• Attacks whole grain in the field and in storage
• Bigger problem in crib corn
• Each moth lays about 40
Photo credit: USDA
• Each moth lays about 40 eggs.
• Larvae bore into grain kernels . Grow to ¼ inch.
• Webbing associated with damage.
• Life cycle is about one month.
Photo credit: Clemson University
Secondary Pests
• Broken, damaged grain and dust
• Usually follow primary feeders
– Beetles
• Flat and Rusty Grain Beetles• Flat and Rusty Grain Beetles
• Confused and Red Flour Beetles
• Saw-toothed Grain Beetles
– Moths
• Indian Meal Moth
Secondary Feeders
Beetles
• Very small beetles
1/12 - 1/7 inch long
• Dark colored beetles
• Light colored larvae• Light colored larvae
• 1/8 - 1/4 inch longSawtoothed grain beetle
Secondary FeedersMoths
• Moths have ¾ inch
wing span.
• Larva pale colored
Prolegs present• Prolegs present
• Surface feeder, may
web over grain.
Secondary Pests
• High moisture, poorly conditioned grain
– Foreign grain beetle
– Hairy fungus beetle
– Black fungus beetle– Black fungus beetle
Factors Affecting Stored Grain
Insect Damage
• Moisture Content of Grain: higher moisture results in higher insect populations.
• Temperature
• Time: the longer grain is held, the higher the • Time: the longer grain is held, the higher the probability of an insect problem.
• Access: insects move into storage facilities after harvest. Seal and screen.
Stored Grain Insects
• Optimum moisture range: 12 to 16%– Exception: Lesser grain borer: 8-9%
• Critical temperature range: 77 to 92 F– Below 70 F: insect reproduction reduced– Below 70 F: insect reproduction reduced
– Below 50 F: insects dormant
• Insect population growth can be reduced by maintaining grain in a cool, dry condition.
Stored Grain Insects
Prevention• Remove (brush, sweep or vacuum) insect-infested
grain and debris from combine, truck beds, transport wagons, augers, grain dumps and other grain handling equipment prior to harvest.
• Remove (brush, sweep or vacuum) grain debris from • Remove (brush, sweep or vacuum) grain debris from empty bins.
– Includes fans, exhaust and aeration ducts.
• Remove all vegetation and debris within 10 feet of the outside of grain bin.
• Spray the inside of the storage bin with a residual insecticide.
Empty Grain Bin Treatment
• Recommended insecticides
– Tempo
– Storcide ll
– Malathion (?)– Malathion (?)
• Spray wall surfaces, floors, braces, ledges
• Spray outside perimeter
Grain Protectant Treatments
• Applied as grain is being augured into grain bin.
• Recommended Insecticides
– Storicide II: rice, wheat, grain sorghum, oats
– Actellic: corn and grain sorghum– Actellic: corn and grain sorghum
• High temperatures and high moisture content
will shorten residual life of protectant
insecticide.
• Do not apply grain protectant before high
temperature drying.
Top-Dress or Surface TreatmentsPrevent Surface Feeders
• Mix into top 4 to 12 inches of grain
– Actellic
– Bacillus thuringiensis (moth caterpillars)
• Dichlorvos (vaponna) strips- Indian • Dichlorvos (vaponna) strips- Indian meal moth
Fumigation
• Infested grain, i.e. weevils and lesser grain borer
• Adding new grain to old grain: fumigate old
• Complicated and potentially hazardous• Complicated and potentially hazardous
• Aluminum phosphide (Phostoxin ® and others)
• Highly effective
• No residual